This study is intended to measure and explain the effect of vertical categorization (regionally integrated transfer agreements) on cost, outcome and actual transfer practice in emergency care. Categorization is the independent variable of most interest but we will also examine the effect of EMT training, aggressiveness of inpatient treatment, speed of response and quality of care. Federal EMS funds are running out. States must soon decide which components of the EMS system will continue to be supported. Recent research seems to support the efficacy of EMT training, rapid response time and (for trauma) aggressive inpatient therapy. On the other hand, little research has been done on the effectiveness of the politically controversial and potentially expensive categorization component. The proposed research will collect abstracts of 20,000 cases, over a 5-1/2 year retrospective and prospective period. Hospitals involved will include 20 from Maine (where vertical categorization is regionally integrated into an advanced EMS system), 15 from the Green Bay area of Wisconsin (where vertical categorization system has recently been initiated) and 15 from the Madison area of Wisconsin (where no formal vertical categorization exists). Severity indices developed at the University of Wisconsin will be used to stratify patients into comparable groups. Quality indices will be used to rate acceptability of care. Multivariate analysis will estimate the effect the independent variables (categorization, as well as EMT training, aggressiveness of therapy, response time and quality of care) on cost, outcome and actual transfer practice. Site visits, implicit record review and epidemiological analyses will be used to help explain results. Implications for improving the EMS system via mixes of transfer agreements (categorization) and institutional upgrading will be drawn.